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better MPG into head wind than cross wind. aerodynamics?

Discussion in 'Prius c Main Forum' started by priustexasbob, Dec 24, 2018.

  1. priustexasbob

    priustexasbob Member

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    I went out of town this weekend and started off with a strong cross and very slightly head wind (15-20 mph steady) my instantaneous mpg ran about 38-43 at 70 mph and RPM was 2400-3200. after 100 miles I turned south into the same strong wind but this time it was directly head wind which I could tell by large US flags (20x40ft) nearly straight out and parallel to direction of travel. this time running 70 mph my mpg was 45-52 and rpm 1600-2400. I know the C is not arrow shaped but getting much better mpg and less rpm into a strong head wind than a cross wind kinda defies logic. the only thing I can figure is the cross section of C caused more rolling resistance than a head wind.
     
    #1 priustexasbob, Dec 24, 2018
  2. bisco

    bisco cookie crumbler

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    I think you’re onto something, pushing the tires on edge probably creates a ton of friction
     
    #2 bisco, Dec 24, 2018
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  3. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    I agree.
     
    #3 JimboPalmer, Dec 24, 2018
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  4. bisco

    bisco cookie crumbler

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    Thanks jumbo!
     
    #4 bisco, Dec 24, 2018
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  5. fuzzy1

    fuzzy1 Senior Member

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    It fits what is known about the Gen2, for which a simulator was linked here long ago. Included somewhere was a graph of air drag vs wind angle, and crosswinds were clearly worse than direct headwind.

    I suspect it means that wind tunnel testing and tuning optimized for direct headwind. The designers ignored crosswinds, and the optimizations start falling apart in those conditions. When the wind starts hitting the side, the angle also increases the aerodynamic cross section.
     
    #5 fuzzy1, Dec 24, 2018
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  6. priustexasbob

    priustexasbob Member

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    thanks for the replys. I figured it musta been something with crosswinds.
     
    #6 priustexasbob, Dec 26, 2018
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